Black Americans suffer disproportionately from hypertension (HTN) and HTN-related end stage renal disease (HTN-ESRD). An increasing but inconclusive body of evidence suggests that anti-HTN therapy and, more specifically, the use of certain classes of anti-HTN agents, namely angiotensin converting enzyme inhibitors (ACEI) and calcium channel blockers (CCB), may retard the progression of renal insufficiency and thereby delay or prevent the onset of HTN-ESRD. In response to RFA-DK-9l -06 (Kidney Disease and Hypertension in Blacks), investigators from the Johns Hopkins Health Institutions propose to collaborate in the design and conduct of a pilot study which, if successful, would proceed to a full-scale, clinical trial testing the efficacy of these two prevention strategies. The proposed pilot will be a double-blind clinical trial in which eligible participants are randomized to one of three step-care interventions (diuretic-, ACEI-, or CCB-based anti-HTN therapy). The study population (70% black) will consist of hypertensive men and women between the ages of 25 and 54, who have a mean glomerular filtration rate (GFR) between 25 and 80 ml/min/1.73 M2. The one year intervention period will consist of two 6 month phases. During the first phase, the goal of therapy will be a diastolic BP of 80-89 mmHg. During the second phase, participants will continue their assigned step-care regimen, but the goal of therapy will be a diastolic BP of 65-74 mmHg. The principal endpoints will be the change in GFR and morphologic changes detected on serial kidney biopsies. Among the strengths of this application are a multi-disciplinary research team. with acknowledged expertise in epidemiologic and therapeutic aspects of HTN and HTN-ESRD; extensive experience in the design and conduct of collaborative clinical trials,, the participation of two Hopkins General Clinical Research Centers; and a proven track record in the recruitment of black participants in NIH-supported, clinical trials of anti-HTN therapy. The investigators look forward to an active role in this important research effort.